SV: Re: SV: Re: [sdiy] Compensating PTC and NTC resistors
controlvoltage at gmail.com
Wed Mar 19 17:50:25 CET 2008
>> Any non-trivial circuit will be difficult to understand the *complete*
>> picture. That's why we make approximations. The temp.co resistor is just
>> one such approximation. It gets us "close enough" to perfection at minimal
>Approximations are not always a neat solution to a problem.
>Making approximations on saftey critically systems are dangerous
>engineering behavior.Close enough are no cigar.
There is nothing wrong with either of these statements, but I question
their relation to each other. Specifically, if you are designing
critical safety systems whose success/failure depends upon knowing the
exact TC of the carbon resistors, maybe your design isn't safe enough.
In that case, I assume that an approximation would be used to
estimate the "absolute worst possible case" of temperature drift, to
be sure that your design could not be negatively affected by this
I apologise for not contributing usefully to this discussion.
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